The present disclosure relates to semiconductor devices and a method of forming semiconductor devices. As one example of scaling techniques for increasing the density of integrated circuit devices, a multi-gate transistor has been proposed, in which a fin-shaped or nanowire-shaped silicon body is formed on a substrate and a gate is then formed on a surface of the silicon body. Because the multi-gate transistor uses a three-dimensional (3D) channel, scaling of the multi-gate transistor may be relatively easily achieved. In addition, current controlling capability can be improved even without increasing a gate length of the multi-gate transistor. Further, a short channel effect (SCE), in which an electric potential of a channel region is affected by a drain voltage, can be reduced.